Spark plug



March 4,1941. G. c. BARNES SPARK PLUG Filed ADIlL 24, 1940 INVENTOR GEEPZ CBHIJJBS /m/u 9 M ATTORNEY Patented Mar. '4, 1941 v UNITED STATES PATENT OFFICE- sraax PLUG Gilbert 0. Barnes, Manchester, Conn., assignor to United Aircraft Corporation, East Hartford, Conn, a corporation of Delaware Application April 24, 1940, Serial No. 331,435 7 Claimm (Cl. 123-469) This invention relates to improvements in the sleeve 38 and the gland l6 and may be sespark plugs for internal combustion engines and cured to or formed integrally with the sleeve and has for an object the provision at means for may rest upon an annular internal shoulder ll automatically controlling the temperature of provided in the gland l6 to-restrain the center the sparking end oi aspark plug of the character electrode against lengthwise movement relative 6 mdicated, to the supporting portion of the spark plug. A

A somewhat more specific object resides in the body oi insulating material 48 may surround the provision in a spark plug or the character indilower portion of the sleeve 36 and bear at its opcated of means for automatically controlling the posite ends against the annular shoulder 44 and 10 heat dissipation from the flring end of the plug the washer 38 and another body 48 of insulating 10 in accordance with the amount of heat absorbed material may surround the upper portion of theby the plug. sleeve 38 and bear at its end on the top of the Other objects and advantages will be more gland l8 and the under surface of the terminal particularly pointed out hereinafter or will be- 84, these bodies of insulating -materials serving come apparent as the description proceeds. additionally to locate the center electfode in the In the accompanying drawing, in which like supporting structure against lengthwise (movereference numerals are used to designate similar ment relative thereto. a; parts throughout; there is illustrated a suitable Within the bore of the hollow center electrode mechanical arrangement for the purpose or dis- 3! there is disp sed a stack of transversely arclosing the invention. The drawing, however, ranged copper discs 50 having their adjacent 20 is for the purpose of illustration only and is not faces in contact with each other, one end of the to be taken as limiting or restricting the invenstack being in contact with theflring point of tion as it will be apparent to those skilled in the the center electrode and the other end being in art that various changes in the illustrated concontact with the inner end of a plug 2 Scr w struction may be resorted to without in any way threaded into the outer or upper end of the cen- 25 exceeding the scope of the invention. ter electrode. The material of the center telec- In the drawing, the single figure is a vertical trode has a somewhat diflerentcoefllcient or heat sectional view through a spark plug constructed expa t an "-19 e pa s on coefllcient of the according to the invention. copper discs, the coeflicient oi the discs preter- Referring t th drawing in detail, the numably being somewhat greater than the coemcient 30 eral. l0 generally indicates a shank or base porof heat expansion of the electrode, and the plug tion having external screw threads l2 on one end B2 is adjusted t0 p y a y ht Predeterportion for engagement with the screw threads mined pr u to h s k of discs when the in the spark plug aperture in an engine cylinder Spark plug is cold. With this arrangement.

head, internal screw threads I at the opposite when the plug is cold there will be only a light 35 end for the reception of the external screw contacting pressure between the adjacent surthreads provided on a gland nut l8, an annular faces of the discs comprisin t Stack within shoulder I8 for compressing a plug sealing gasthe hollow electrode and the stack will, there ket and a polygonal wrench reception portion 20. fore, be a relatively poor conductor of heat. As

Q The gland nut l8 has a'polygonal wrench rethe D 11! heats up, h v due to the unequal 40 ception portion 22 and a beveled end portion 24 at efl e t heat e p sion, the attack will exthe opposite end which cooperates with a beveled ban S mewhat m r rapidly, than the electrode internal shoulder 26 in the base member Ill to i and the pressure between the adjacent discs will compress' packing 23 t provide a fluid tight increase and the heat conduction capacity of the Seal between the members m and m stack will correspondingly increase so that heat 45 Within the members l6 and I8 there is a subwill be more rapidly removed from e fi ng stantially coaxial hollow core member 80 prop t en o center electrode d d s pated vided at one 'end with a enter electrode 32 and from the end of the Pl c rryin the terminal surrounded at the opposite end by a cable ter- 84.

minal' 34. This center electrode may be sur- With this arrangement the firing end of the I rounded by a sleeve 38 01' insulating material beplug, which projects within the combustion tween the terminal 34 and a washer 38 disposed chamber of the engine cylinder, will heat up very against an annular shoulder 40 on the end porrapidly to its operating temperature since most tion of the electrode 32 Insulating material 42, of the heat of the first few explosions will'remain formed in one or more pieces, is applied between in the firing end of the plug, but as soon as the ,5

I optimum operating. temperature the stack of discs will have expanded until the stack functions as a good heat conductor and thereafter removes the excess heatfrom the firing end of the plug at a ratewhich prevents the firing end ture.qf,-. I

While copper has been mentioned as a suitable material for the discs and it is wellknown that some steel alloy such as, nickel or tungsten steel are usually used for the center electrodes -of sparkplugs, it is to be understood that the in- -from exceeding the desired operating temperavention is not to be limited to these particular materials but that various other combinations may be used which will perform substantially the same function, the principal consideration being that the material of the discs should have a somewhat greater coefiicient of heat expansion than the material 01' the center electrode and that the material of the discs should be a relatively efllcient conductor of heat.

While a particular structural embodiment has been hereinabove described and illustrated in the accompanying drawing, it is to be understood that the invention is not limited to the particular embodiment so described and illustrated, but that such changes in the size, shape. and arrangement of the various parts may be resorted to as come within the scope of the sub-joined claims.

Having now described. the invention so. that others skilled in the art may clearly understand the same, what it is desired to secure by Letters Patent is as follows:

' 1. In an engine spark plug, a center electrode having a longitudinalbore therein, and a stack 01' plates of a material having a relatively high heat conductivity disposed in said bore.

' 2. In an engine spark plug, a center electrode having a longitudinal bore therein, and a stack of discs or a material having a relatively high heat conductivity and a coeflicient of heat expansion greater than the heat expansion coefficient of said center electrode disposed in said bore, and a relatively fixed abutment for each end of said stack.

3.. Temperature regulating means for a spark plug having a hollow center electrode comprising, a stack of metal plates in said electrode of a material havingfa heat expansion coeflicient' the other abutment comprises a plug screw threaded into the open end of said electrode.

6. The arrangement as set forth in'claim 3 in which the main ingredient of said plates is copper.

7. The arrangement as set forth in claim 3 including a cable terminal on the outer end of said center electrode and in which said stack extends to a location within saidcable terminal;

GILBERT C. BARNES. 

